Efficient land-based fish farm

ABSTRACT

Efficient fish farming techniques are described, including a land-based saltwater flow-through pool fed by seawater intakes, and efficient water flow and waste removal techniques that promote good fish growing conditions. Features include devices for encouraging laminar flow in the flow-through pool, and efficient waste removal, and multiple seawater intakes from different ocean depths.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/384,312, filed Apr. 15, 2019, which claims benefit under 35 U.S.C. §119(e) of Provisional U.S. Patent Application No. 62/657,582, filed Apr.13, 2018, the contents of which is incorporated herein by reference inits entirety.

BACKGROUND

This disclosure relates to aquaculture technologies.

Aquaculture includes controlled aquatic conditions for the farming ofaquatic organisms such as fish. Aquatic conditions may be controlled bycontaining the aquatic organisms or by control of the water in whichthey are farmed. A typical saltwater fish farm includes a net-pen or afixed cage containing saltwater fish at an ocean location, where waterfrom the surrounding ocean environment naturally flows through thenet-pen or cage to provide fresh oxygenated water to the contained fishand to remove fish and feed waste. A land-based fish farm may include acircular tank of spinning water where centrifugal forces separateeffluent from cleaner water. A center drain in the tank typicallyremoves most of the settled waste particles by draining just 10-15% ofthe effluent, while a side drain at the water surface discharges theremaining effluent from the cleaner water.

Atlantic salmon are commonly farmed using a combination of land-basedand open ocean farms. In their early life stages, salmon are freshwateranimals know as fry or fingerlings that are grown in freshwater tanks.The fry become saltwater animals known as smolts during theirsmoltification stage and at a weight of 40-50 grams for Atlantic salmon.This strain of salmon is then transferred to a saltwater farm, which istypically an ocean net-pen at a location with water temperatures thatpromote adult salmon growth, until harvested at around 4.5 kilograms perfish.

Many factors may affect the productivity, efficiency, and efficacy of afish farm. Fish farm productivity may be measured by the amount of fishharvested, such as by weight or in the length of time needed for a fishto achieve a weight or other growth milestones. Fish farm efficiency isthe amount of resources, such as power, feed, time, or water needed togrow a certain amount of fish. Some factors affecting productivity andefficiency include water temperature, genetics, waste treatment, type offeed used, water cleanliness inside the containment, and lack ofdiseases at the farm. For example, a preferred water temperature rangein the fish containment may encourage faster fish growth leading tohigher productivity. Salmon are healthiest and grow fastest in a watertemperature range of 7 to 13 degrees Centigrade; above or below thatrange is not optimal.

The inventors perceive a need for improvements in fish farmingtechnologies, including improvements in productivity and efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an overview of an example of a seawater aquaculturesystem.

FIG. 2 depicts an example of a sea water intake system.

FIG. 3A depicts a top-down view of a seawater mixing system.

FIG. 3B depicts a perspective view of the seawater mixing system of FIG.3A.

FIG. 3C depicts an end view of the seawater mixing system of FIG. 3A.

FIG. 3D depicts four cut-away views of the mixing system of FIG. 3A

FIG. 4 depicts a cross section of a seawater mixing system of FIG. 3A.

FIG. 5 depicts an example flow shaping structure with a dish.

FIG. 6 depicts an example schematic of a flow shaping structure.

FIG. 7 depicts an example flow shaping structure with a frame.

FIG. 8A depicts an example flow shaping structure with wall-mountedspoilers.

FIG. 8B depicts an example perspective view of flow shaping structurewith wall mounted spoilers.

FIG. 9 depicts an example flow shaping structure with spoilers.

DETAILED DESCRIPTION

This disclosure describes efficient fish farming techniques, including aland-based saltwater flow-through pool fed by seawater intakes, andefficient water flow and waste removal techniques that promote good fishgrowing conditions. Embodiments include techniques for encouraginglaminar flow in a flow-through pool, such as a fish raceway. Laminarflow may provide efficient water flow through the fish farm and mayprovide efficient waste removal techniques by controlling movementthrough the pool of waste such as fish excrement and uneaten feed.Reduced turbulence may reduce energy needed to pump water through apool. Laminar flow may more effectively and reliably deliver oxygen tofish in the pool as compared to a more turbulent flow or flow witheddies or water mixing in a direction perpendicular to the direction offlow. Laminar water flow may move waste, such as uneaten feed and fishexcrement, more predictably through the pool and into waste collectionsystems, such that waste may be concentrated into a first portion ofwater removed from the tail-end of the pool, while a second portionremoved at the tail-end of the pool may have less waste. The secondportion of water may then be returned to an open water source, such asthe ocean, with minimal filtering or treatment. Thus, the amount ofrequired filtering and treatment for waste may be reduced as compared toprior techniques by reducing the proportion of effluent needingtreatment. In some embodiments, the first portion may drain from thenear the top and bottom of the pool, while the second portion may drainfrom a middle depth of the pool. Laminar flow may also waste fromreaching the headend of a flow-through pool, preventing bacteria growthor other types of contamination around headend structures.

Structures that may encourage laminar flow of seawater or fresh waterthrough a flow-through pool include a dish positioned in front of aseawater inlet at the headend of the raceway, for example with concaveor a parabolic surface facing the inlet, for redirecting current flowoutward away from the inlet along the headend wall, a frame wallsurrounding the inlet for redirecting current flow inward back towardthe inlet, and a pressure filter for creating an antechamber at theheadend of the raceway. In embodiments with multiple seawater inlets atthe raceway headend, the frame wall may divide the headend wall intosections.

Other embodiments include multiple seawater intakes positioned atdifferent depths in the ocean where, for example, a first intake may bepositioned to receive water from an ocean current with a watertemperature favorable to a breed of fish in a fish farm and a secondintake may be positioned at depth that precludes intake of watercontaminated with certain parasites. Seawater from different depths maybe different temperatures, and mixing the different temperatures mayprovide improved growth conditions for fish in a flow-through pool.

Some embodiments may reduce parasite infestation. Traditional saltwaterfish farms such as a purse seine-like net-pen in open water allows freeflow of water into and out of the net-pen. This may allow some removalof farm waste from the net-pen with a minimum of effort, but there canbe many problems with such as system. Frequent disease outbreaks,infestation by parasites such as sealice, and other environmental issuesmay be common for such open ocean flow-through pens. In addition, farmwaste may collect on the ocean floor underneath the pen, which may thencreate bad environmental effects such as H2S gasses. Techniquesdisclosed herein mitigate many of these problems.

Embodiments include methods for growing aquatic organisms such as fish,including creating or inducing a laminar flow or substantially laminarflow of fluid through a flow-through pool, such as by using one of moreof the various laminar-flow inducing devices and structures describedherein. These embodiments may include raising aquatic organisms in thelaminar flow of the pool, and may include using the laminar flow toremove waste from the pool. Some embodiments may include preventingcontamination by waste and feed of an antechamber at the headend of thepool. Such an antechamber may be created by a pressure filter at theheadend of the pool, upstream from where feed is introduced to laminarflow.

FIG. 1 depicts an overview of an example of a seawater aquaculturesystem 100. A flow-through pool is a type of land-based fish farm.Saltwater fish may be grown on land in an inland flow-through pool fedby sea water which is then drained back to the sea. In FIG. 1 , seawatermay generally flow from left to right. Seawater intakes 166 and 168 maybe positioned at different depths and below a depth 102 in ocean 150.Intakes 166 and 168 may feed a seawater mixer 164, whose output may becontrolled by a valve 104 and pump 106 to provide seawater to inlets 162at the headend of flow-through pool 152. Dishes 158 may be positioned infront of inlets 162 to redirect flow 160 from inlets 162. Pressurefilter 156 may define an antechamber at the headend of pool 152 andseparate fish 114 from inlets 162. Feeder 108 may drop feed 110 intopool 152. Seawater may flow 154 through pool 152 from the headend (onthe left of FIG. 1 ) to the tail-end (on the right of FIG. 1 ).

The surface height 112 of water in the pool 152 may substantially matchthe surface height of ocean 150. Head pressure behind pressure filter156 built from pump 106 may cause the water surface height in theantechamber, before the pressure filter at the headend of the pool 152,to rise slightly above the surface height on the other side (downstreamside) of pressure filter 156. In some embodiments, the pool surfacelevel 112 may rise and fall with the tides of ocean 150. For example, apool depth from the bottom of the pool to the pool surface level 112 maybe 20 meters, while tides rise and fall 1.5 meters on average.

Pool 152 may be rectangular in shape. As compared to prior racewaysystems, a flow though-pool may have different proportions. For example,an embodiment of this disclosure may be deeper, shorter from headend-totail-end, and wider from side to side as compared to prior racewayssystems. Additionally, flow speed of fluid in the pool may be slowerthan raceway system. Such differences may be enabled by the laminar flowto eliminate problems such as waste removal in prior raceway systems.Some differences, such as slower speed fluid, may enable in-land growthof fish that typically are raised in open water pens, such as adultsalmon, which are not accustomed to the high currents of prior raceways.

The amount of water flowing through the pool 152 can be substantial.Dimensions of many pool elements, such as the inlet, parabolic dish, anddistance of the parabolic dish and filter from the headend wall, may allbe based on how a required flow rate of water. The required flow rate ofwater may be based on the amount and type of fish in the pool. Salmon,for example, may require 0.3 liters per minute of water to flow thoughthe pool for every fish in the pool. In one example, a pool 152 may be20 meters deep from water surface 112 to floor, meters wide, and 50meters long from headend to tail-end, with the entire volume of watercontinuously replaced every 30 minutes. To provide that much water atthe headend, a flow-through pool may have a pair of inlets 162, witheach inlet being a circular opening 2 meters in diameter. The dish 158may have a parabolic concave surface or may be paraboloid in shape, andmay be 3 to 4 meters wide in diameter from edge to edge, and resistancefilter 156 may be 3 meters from the headend wall of the pool. Filteringor otherwise treating such a volume of water may be challenging andexpensive. Waste treatment efficiency can be improved by dividing thepool outflow into a cleaner portion requiring less treatment filtering,and a dirtier portion requiring more treatment or filtering. Embodimentsof the aquaculture system 100 may require only 10% to 20% of the totalpool outflow to be filtered via settling tank 121.

A first portion 144 of the pool water may be collected at drain 142positioned toward the bottom of the tail-end of pool 152 and fed througha pump 140 to settling tank 121 or another type of waste treatment orremoval system. Settled waste 124 may be collected in settling tank 121and be removed by filter 126 to create cleaner water. Cleaned water maybe drained by outlet 132 from settling tank 121 and returned to ocean150 via outlet diffuser 130. Collected waste 128 may be dried and usedas fertilizer for crops or burned to create energy.

A second portion 146 of pool water may be collected via drain 138 to bereturned to ocean 150 via outlet 132 without passing through a settlingtank or otherwise cleaned or treated. In some situations, a pump 136 andor valve 134 may be used to control effluent from the second portion 146of water.

In some embodiments, additional pool waste may be collected by cleaningrobot 148 and floating skimmer 118. Cleaning robot 148 may remove wastesettled on the bottom of the pool 152, for example by moving around thebottom of the pool 152. A pump (not depicted) may suck water from mobileor robotic suction head on the bottom of the pool to capture waste nearthe bottom or settled on the floor of the pool. Floating skimmer 118 mayfloat to collect floating waste and move up and down as water level 116in the pool moves up and down, such as with the tides of ocean 150. Pump120 may suck water and waste into floating skimmer for treatment, suchas in setting tank 121.

FIG. 2 depicts an example of a sea water intake system 200. Intakes 208and 210 receive seawater from the ocean. Intake control 206 controls theproportion of water from intakes 208 and 210 that are used to supplyseawater to a land-based fish farm via pipe 204. Intake 210 may be apipe with an opening at a depth d2 below the average sea level surface,where depth d2 is between depths d1 and d3. Intake 208 may be a pipewith an opening at depth d4 below the water surface, where depth d4falls below depth d1 and above depth d2. Intake control 206 may controlmixing of the intakes via a variable mixer (not depicted). By varyingthe proportion of ocean water sourced between intakes 208 and 210,intake control 206 may vary the proportion of water from ocean depths d2and d4 that enter an intake channel for a land-based fish farm via pipe204. In this way the temperature and other seawater properties outputfeed into the pool may the result of such a mixture. In otherembodiments, intake control may simply select between intake 208 and210.

Desirable properties of ocean water, including desirable temperatures,may vary with depth in an ocean. A large-scale ocean current, such ascaused by thermohaline circulation and including meridional currents,may move warmer water from near the equator toward the earth's poles,and may move cold water at the poles toward the equator. For example,temperate water may move north-east in the Gulf Stream ocean current(from the Gulf of Mexico up to the North Atlantic) in combination withthe North Atlantic Drift ocean current (eastward across the NorthAtlantic) and the Norwegian ocean current (from the North Atlantic Driftup the coast of Norway to above the Arctic Circle).

Depths d1 and d3 may define a range of depths within which an oceancurrent flows having properties desirable for a fish farm. Between thedepths of d1 and d3, water from southern oceans may be delivered tonorthern latitudes at certain times of the year. For example, the GulfStream ocean current may reach parts of the Norwegian coast at a depthbelow 120 meters, where the Gulf Stream may have water temperaturesbetween 6 and 8 degrees Celsius even in winter with a stable salinity of3.3-3.4% and a surface temperature of 1-2 degrees Celsius. Waterproperties such as these may be desirable for a fish farm. Generallywarmer water temperatures up to 13 degrees Centigrade may promote fasteror better fish growth, leading to higher fish farm productivity.

A fish farm may obtain saltwater primarily from intake 210 in thesummer, and then primarily from intake 210 in the winter, to promotefish farm productivity in all seasons. During the summer, water closerto the surface may have temperatures higher than temperatures in theocean current. For example, summer ocean surface temperatures on partsof the Norwegian Arctic coast may reach 12 to 13 degrees Celsius.However, water close to the ocean surface may have other undesirableproperties, such as presence of organisms or pollutants that mightinfest or otherwise adversely affect fish in a fish farm. Depth d5 maybe a depth below which seawater does not have an undesirable property.For example, sealice, which are a regulated pest for salmon farms, maynot occupy sea water at depths below 25 meters below the ocean surface.Hence, by accepting water below depth 25 meters, intakes 208 and 210 mayreceive only water that is free of sealice.

FIG. 3A-3D depict different view of a seawater mixing system 300. FIG.3A depicts a top-down view of the mixing system 300. Mixing system 300includes a first inlet pipe 304 and second inlet pipe 314, which areconnected to the input side of mixing pipe 306. The output side ofmixing pipe 306 is connected to a first outlet pipe 312 and a secondoutlet pipe 308. Mixing system 300 may be used, for example, to mixwater from two seawater intakes as in mixer 164 of FIG. 1 or intakecontrol 206 of FIG. 2 . A first fluid 302 may flow in first inlet pipe304, and a second fluid 316 may flow separately through separate secondpipe 314. Inside the mixing pipe 306 first fluid 302 and second fluid316 may be merged to create mixture of fluids 302 and 316 that flowsthough both outlet pipes 308 and 312. As can be seen from in theperspective view of FIG. 3B, after entering mixer 306 from pipe 304,fluid 302 is split into two portions as it is mixed with fluid 316, theseparate portions exiting via different outlet pipes 308 and 312. Thesecond fluid is similarly split in the mixer, with the result beingoutput fluids 310 and 311 in pipes 308 and 312, respectively. Eachoutput fluid 310 and 311 includes a portion of both fluids 302 and 316.As shown in FIG. 3B, inlet pipes 304 and 314 are stacked verticallyside-by-side, while outlet pipes 308 and 312 are arranged horizontallyside-by-side.

FIG. 3C depicts an end view of the seawater mixing system 300 of FIG.3A. This view looks into the open ends of outlet pipes 308 and 312,while the exterior of inlet pipes 304 and 314 are depicted as the inletpipes bend toward the center of mixer 306. Contour lines inside outletpipes 308 and 312 indicate the curve of the interior of these pipestoward the center of mixer 306. The inlet pipes 304 and 314 are arrangedalong axis 340, while outlet pipes 308 and 312 are arranged along axis350, which is perpendicular to axis 340. FIG. 3D depicts four cut-awayviews of the mixing system of FIG. 3A.

FIG. 4 depicts a cross section 400 through at the lengthwise center ofmixer 306 of mixing system 300. The center of mixer 306 is a clover-leafshape where vertically arranged inlet pipes 304 and 314 are merged withhorizontally arranged outlet pipes 308 and 312. As depicted, there areno interior veins or walls inside mixer 306 at its center. This mixerarrangement allows fluids 302 and 316 to mix in a controlled manner,very efficiently, and with little turbulence.

FIG. 5 depicts an example flow shaping structure 500 with a dish.Flow-through pool 504 is fed by water flow 510 through inlet pipe 508.Dish 512 is positioned in front of inlet into headend wall 502 from pipe508. Dish 512 may be curved, starting from a center point farthest fromthe inlet and the pool headend wall 502, back toward the headend wall502. The dish 512 may be a parabolic in shape (or a paraboloid in threedimensions), may be a section of a sphere, or other similarthree-dimensional shape. Dish 512 may cause flow 510, as it exits pipe508, to be redirected radially away from the inlet along the headendwall 502, for example along flows 514 and 516.

Veins 506 at a bend in pipe 508 may reduce resistance to fluid flowaround the bend in the pipe. If an inlet pipe is bent just before anopening to a flow-through pool, veins may be positioned in the inletpipe just at the inlet opening into the pool.

FIG. 6 depicts an example schematic of a flow shaping structure 600.Pipe 602 meets a pool wall 606 at an inlet centered on point 606. Dish612 may be centered on the inlet in that center point 610 of dish 612may be directly in front of the center point 606 of the inlet. A width616 of the inlet may be smaller than the width of dish 612. The angle618 from the center point 606 of the inlet and between the edge 608 ofthe dish and the center point 610 of the dish may be, for example, 45degrees. The distance from edge point 608 to the plane of wall 604 maybe less than half the distance to the from center point 610 to the planeof wall 604.

FIG. 7 depicts an example top-down view of a flow shaping structure 700with a frame. Pipe 708 feeds water flow 710 through an inlet in theheadend wall 702 of a flow-through aquaculture pool. Flow-shapingdevices in the pool of structure 700 may include dish 712, frame wall726 with rounded corners 722 and 724, and pressure filter 720. Optionalspoiler 728 may or may not be included in some embodiments.

Water may enter the pool as flow 710 into the inlet, and may be divertedby dish 712 into an outward flow 732 that flows along the headend wall702 and radially outward from the inlet and perpendicular to the lengthof the pool. Flow 732 may then reflect off frame wall 726 and corners722 and 724 as flow 732, which then may become an inward flow 734. Asflows 732 and 734 pass alone pressure filter 720, the flows may bediverted to exit the headend antechamber defined by pressure filter 720by passing through pressure filter 720 to become flow 718 that flowsalong the length of the pool. Flow 718 may nourish fish in the pool, andbe drained from the tail-end of the pool.

The inlet in wall 702 of pipe 710 may be, for example in the shape of acircle or a square in the headend wall 702. Dish 712 and optionalspoiler 728 may surround the inlet with circular symmetry, while wall726 may surround the inlet in the shape of a rectangle or square.Similarly, pressure filter 720 may be square or rectangular, spanningthe space from one side wall of a pool to another side wall of a pool.In other embodiments, a plurality of inlets in a headend wall may havedishes and frames around each inlet, with the plurality of inlets, dishand frames all behind a single pressure filter.

Rear corner 722 and forward corner 724 may be curved with fillets toshape flow 732. Dish 712 may be positioned between rear corner 722 andforward corner 724, and pressure filter 720 may be further down thepool, past corner 724.

Optional spoiler 728 may tend to encourage part of flow 734 towardpressure filter 720, and may additionally tend to encourage theremainder of flow 734 back between the spoiler and the dish to join flow732.

The combinations of the flow shaping devices in structure 700 at theheadend of a flow-through pool may tend to create a more uniformdistribution of current 718 across a pool, may reduce turbulence inwater as it moves down the pool, and hence these structures mayencourage laminar flow past the fish in the pool. A more laminar flowmay have several benefits, including: better controlled movement ofwaste, such as fish excrement and feed, through a pool making wasteremoval more efficient; reduced turbulence, which may result in a moreefficient flow requiring less energy or pressure to create the flow offluid from headend to tail-end of the pool; and a lack of turbulencenear the output of the pressure filter 720, which may prevent waste frommoving back past the pressure filter and into the antechamber at theheadend, thereby reducing bacterial growth and other related problems ofwaste in the antechamber. These devices may encourage laminar flow inboth freshwater and seawater flow-through systems.

FIG. 8A depicts an example side view of shaping structure 800 withwall-mounted spoilers. Pipe 808 feeds water flow 810 through an inlet inthe headend wall 802 of fish pool. Flow-shaping devices in the pool ofstructure 800 may include dish 812, section divider 852, and pressurefilter 820. Optional spoilers 840, 842 848, and 850 may or may not beincluded in some embodiments. Section divider 852 may separate a firstupper inlet (depicted as output of pipe 808 into the pool) fromadditional lower inlets (not depicted) below the first upper inlet andfurther below the water surface level 804 of the pool.

Optional spoilers 840, 842, 848, and 850 may be arrayed in concentricbroken circles around the inlet (for example as depicted in FIG. 8B). Asin previous figures, dish 812 may redirect flow 810 radially outwardfrom the inlet. Each spoiler, such as 840, 842, 848, and 850, mayredirect a portion of the radial outward current toward pressure filter820. For example, spoiler 842 may redirect a portion of the radialoutward current into current 844 heading generally toward pressurefilter 820 and down the pool.

FIG. 8B depicts an example perspective view of a flow shaping structure860 with wall mounted spoilers. FIG. 8B depicts four sections at theheadend of a pool in a 2×2 array, each section including a dish 862 infront of a square inlet. Channel 888 divides current 876 to flow pastveins into the inlets. For example, current 880 flows through an inletin the lower left section of the flow-through pool 868. Section divider874 is a wall extending from headend wall into the antechamber with alength less than the length of the antechamber. Section divider 874 maytend to keep current from the inlets of different sections from mixingand creating turbulence. Spoilers 872 are arrayed radially in brokenconcentric circles around each inlet. Antechamber frame 870 may holdpressure separate pressure filters for each inlet section.

FIG. 9 depicts an example side view of flow shaping structure 900 withdish spoilers. Pipe 908 feeds water flow 910 through an inlet in theheadend wall 902 of fish pool. Flow-shaping devices in the pool ofstructure 900 may include dish 912, pool side wall 926, and pressurefilter 920. Optional spoilers 928 may or may not be included in someembodiments. Spoiler 928 may be a curved shape proximate to the edge ofdish 912 and may redirect some of the water from inside dish 912 ascurrent 930 back toward pressure filter 920 and not radially along theheadend wall.

1. An aquaculture system comprising: an inlet in a headend wall of aflow-through pool for providing a fluid to the pool; a dish positionedinside the pool and centered on a center of the inlet for distributing acurrent from the inlet along the headend wall; a pressure filtercreating an antechamber at a headend of the pool, wherein the inlet andthe headend wall are in the antechamber; and a spoiler positionedbetween the dish and the pressure filter.
 2. The system of claim 1,wherein the dish is paraboloid in shape.
 3. The system of claim 23,further comprising: a first curved fillet at a joint of the headend walland the frame wall; and a second curved fillet at a joint between theframe wall and the return fin.
 4. The system of claim 23, furthercomprising: a second inlet in the headend wall; and wherein a portion ofthe frame wall bisects the headend wall between the inlet and the secondinlet.
 5. The system of claim 23, wherein a wall of the pool or a floorof the pool form a portion of the frame wall. 6-19. (canceled)
 20. Thesystem of claim 1, wherein the spoiler surrounds the inlet with circularsymmetry.
 21. The system of claim 1, wherein the spoiler includes a holein the center of the spoiler and the hole is centered on the center ofthe inlet.
 22. The system of claim 1, wherein the headend wall and thepressure filter are parallel to each other, and the spoiler is angledrelative to the headend wall and the pressure filter.
 23. The system ofclaim 1, further comprising: a frame wall around the inlet extendingfrom the headend wall and along the pool; and a return fin inside theantechamber and extending inward toward the inlet from the frame wallbetween the headend wall and the pressure filter.